Improve render time for Grass/ Forest? (Eevee)
That what you refer to with

copy the information of this to every other tree

is called &quot;instancing&quot;. If you use a particle system or arrays to distribute your trees and grass, you are already making implicit use of instancing.
If you however use manually placed copies for your trees, you might want to use the option &quot;duplicate linked&quot; (Shortcut: Alt+D), to keep the scene more efficient to store and to render.
Also, generated trees tend to have a LOT of polygons, most of which do not really contribute to the perceived detail (especially if the trees are in the background!).
So it may pay off to use the &quot;decimate&quot; modifier quite drastically on background trees.